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authorEric Dumazet <eric.dumazet@gmail.com>2011-07-11 02:49:52 +0000
committerDavid S. Miller <davem@davemloft.net>2011-07-11 20:25:04 -0700
commit6d1a3e042f55861a785527a35a6f1ab4217ee810 (patch)
treeb8494647164f51135a40b2ffffd37ebb4285a3d8
parent995181b9529adbfecd6882c734ee702b5ed9226c (diff)
inetpeer: kill inet_putpeer race
We currently can free inetpeer entries too early : [ 782.636674] WARNING: kmemcheck: Caught 32-bit read from uninitialized memory (f130f44c) [ 782.636677] 1f7b13c100000000000000000000000002000000000000000000000000000000 [ 782.636686] i i i i u u u u i i i i u u u u i i i i u u u u u u u u u u u u [ 782.636694] ^ [ 782.636696] [ 782.636698] Pid: 4638, comm: ssh Not tainted 3.0.0-rc5+ #270 Hewlett-Packard HP Compaq 6005 Pro SFF PC/3047h [ 782.636702] EIP: 0060:[<c13fefbb>] EFLAGS: 00010286 CPU: 0 [ 782.636707] EIP is at inet_getpeer+0x25b/0x5a0 [ 782.636709] EAX: 00000002 EBX: 00010080 ECX: f130f3c0 EDX: f0209d30 [ 782.636711] ESI: 0000bc87 EDI: 0000ea60 EBP: f0209ddc ESP: c173134c [ 782.636712] DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068 [ 782.636714] CR0: 8005003b CR2: f0beca80 CR3: 30246000 CR4: 000006d0 [ 782.636716] DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000 [ 782.636717] DR6: ffff4ff0 DR7: 00000400 [ 782.636718] [<c13fbf76>] rt_set_nexthop.clone.45+0x56/0x220 [ 782.636722] [<c13fc449>] __ip_route_output_key+0x309/0x860 [ 782.636724] [<c141dc54>] tcp_v4_connect+0x124/0x450 [ 782.636728] [<c142ce43>] inet_stream_connect+0xa3/0x270 [ 782.636731] [<c13a8da1>] sys_connect+0xa1/0xb0 [ 782.636733] [<c13a99dd>] sys_socketcall+0x25d/0x2a0 [ 782.636736] [<c149deb8>] sysenter_do_call+0x12/0x28 [ 782.636738] [<ffffffff>] 0xffffffff Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/ipv4/inetpeer.c14
1 files changed, 9 insertions, 5 deletions
diff --git a/net/ipv4/inetpeer.c b/net/ipv4/inetpeer.c
index dafbf2c98b28..90c5f0d1bcf3 100644
--- a/net/ipv4/inetpeer.c
+++ b/net/ipv4/inetpeer.c
@@ -373,11 +373,14 @@ static int inet_peer_gc(struct inet_peer_base *base,
while (stackptr > stack) {
stackptr--;
p = rcu_deref_locked(**stackptr, base);
- delta = (__u32)jiffies - p->dtime;
- if (atomic_read(&p->refcnt) == 0 && delta >= ttl &&
- atomic_cmpxchg(&p->refcnt, 0, -1) == 0) {
- p->gc_next = gchead;
- gchead = p;
+ if (atomic_read(&p->refcnt) == 0) {
+ smp_rmb();
+ delta = (__u32)jiffies - p->dtime;
+ if (delta >= ttl &&
+ atomic_cmpxchg(&p->refcnt, 0, -1) == 0) {
+ p->gc_next = gchead;
+ gchead = p;
+ }
}
}
while ((p = gchead) != NULL) {
@@ -456,6 +459,7 @@ EXPORT_SYMBOL_GPL(inet_getpeer);
void inet_putpeer(struct inet_peer *p)
{
p->dtime = (__u32)jiffies;
+ smp_mb__before_atomic_dec();
atomic_dec(&p->refcnt);
}
EXPORT_SYMBOL_GPL(inet_putpeer);

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